jQuery中focus()和focusin()、focus()和children()的差别
focus()和focusin()
focus()和focusin()的差别在于focusin()支持事件的冒泡。以下举例说明：
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>focusin demo</title>
<style>
span {
display: none;
}
</style>
<script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
<p><input type="text"> <span>focusin fire</span></p>
<p><input type="password"> <span>focusin fire</span></p>
<script>
$( "p" ).focusin(function() {
$( this ).find( "span" ).css( "display", "inline" ).fadeOut( 1000 );
});
</script>
</body>
</html>当我们点击输入框时。其获得焦点。导致获得焦点事件向上冒泡，使得p标签触发获得焦点事件，而focus()并不支持事件冒泡，相同地。focusout()支持事件冒泡，而blur()不支持。
find()和children()
find()和children()的差别在于find()向下追溯多级子节点，而children()仅仅向下追溯一级子节点。find()和children()相同的地方是他们在寻找子节点时都不包括自身节点。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
p{
font-size: 20px;
width: 200px;
color: blue;
font-weight: bold;
margin: 0 10px;
}
.hilite {
background: yellow;
}
#test{
font-weight: bolder;
}
</style>
</head>
<body>
<ul class="level-1">
<li class="item-i">I</li>
<li class="item-ii">II
<ul class="level-2">
<li class="item-a">A</li>
<li class="item-b">B
<ul class="level-3">
<li class="item-1">1</li>
<li class="item-2">2</li>
<li class="item-3">3</li>
</ul>
</li>
<li class="item-c">C</li>
</ul>
</li>
<li class="item-iii">III</li>
</ul>
<script src="jquery-2.1.4.js"></script>
<script>
$( "li.item-ii" ).find( "li" ).css( "background-color", "red" );
</script>
</body>
</html>倘若将上例中的find()替换为children()，会得到不同的结果。